Filament support



June 7, 1932. R. M. HEINTZ FILAMENT SUPPORT Filed Jan. 26, 1931 INVENTOR, RALPH M. HE/NTZ.

ATTORNEY Patented June 7, 1932 UNITED STATES PATENT; OFFICE RALPH M. nnrnrz, or PALO ALTO, CALIFORNIA, ASSIGNOR TO nnin'rz aKAUrMAN,

' m n, or sen rzeanorsco, camronnm, a conronnrron or NEVADA FILAMENT SUPPORT Application filed January 26, 1931.v Serial No. 511,277.

w, tion in a filament tensioning member; third,

to provide a spring filament tension member wherein the spring portion is maintained in a relatively low temperature in spite of the high temperature of the filament with which the support is in contact; and fourth, to pro vide a filament tensioning support which is rigid and which is easily assembled.

Other objects of my invention will be apparent or will be specifically pointed outin the description forming a part of this specification, but I do not limit myself to the embodiment of my invention herein described, as various forms may be adopted within the scope of the claim.

The single figure of the drawing, which is partly in section and partly. in elevation, shows the filament support of my invention as applied to a power vacuum tube. To avoid confusion in the drawing, only the filament structure within the tube is illustrated, the other tube elements being omitted.

In vacuum tubes using filamentary cathodes, it is important that a moderate but substantially constant tension be applied to the filament in order to compensate for its thermal expansion and contraction, and to keep it at all times in substantially the same plane. Various structures have been used to accomplish this result, but most of these structures have had two major disadvantages If short springs, mounted closely adjacent to the filament are used, the transfer of heat from the filament tends to overheat the spring and make it lose its resiliency; this difiiculty may be partially overcome by interposing a relatively long straight portion or tie between the spring and the filament, but this ar rangement increases the tendency of-the fila ment to vibrate, with resulting microphonic action of the tube. Both of these difficulties are; largely obviated by the use of my invention.

The means which I employ may best be appreciated with reference to the drawing, whereinis shown the usual evacuated envelope 1, within which the V-shaped fila-. ments 2 are mounted upon the supporting leads 3, sealed through the stem 4. The filament leads connect with contacts 6 mounted upon the usual tube base 7.

Projecting inwardly from the opposite end of the envelope is a stud or boss 8, the end of which is preferably somewhat expanded to form a flattened head 9.

Surrounding the stud above its flattened head is a split clamp 11, held in place by a screw or other suitable fastening means 12. Welded to the clamp and arched over the end of the-stud is a supporting frame or yoke 13. A transverse bar or support member 15 extends across the frame, whose sides ire perforated to support the ends of the The filament supports themselves comprise the substantially straight tie portions 16, whose ends are hooked to engage the filament, and the spring portions 17. The straight tie portions pass through holes 18 formed in the transverse portion of the yoke or frame, and the ends of the supports, above the spring portion 17, are fixed to the trans- It will be seen that the guide holes 18 act to limit and damp out vibration of the filament supports as a whole. The temperature of the spring portions of the supports is maintained at a relatively low value, first by radiation from the long tie portion 16, sec- 0nd, by the fact that the yoke intercepts di rect radiation from the filament, and third, by the fact that the comparatively cool yoke with its high thermal conductivity to the stud 8 absorbs heat from the tie portion and thereby decreases the conduction to the spring.

I claim:

In combination with a filament mounted within an evacuated envelope, a stud projecting into said envelope, a clamp encircling said stud, a metal frame comprising a bar arched over said stud and having its ends secured to said clamp and a guide hole formed in the arched portion, a transverse bar extending across said frame, and a fila ment support secured to said transverse bar and comprising a continuous wire formed with a helical spring portion positioned between the bar and the frame and a. tie portion extending through the guide hole and secured to the filament. V

In testimony whereof, I have hereunto set my hand.

RALPH M. HEINTZ. 

